Metallic vapor device



May 3, 1927.

E. WEINTRAUB METALLIC VAPOR DEVICE Fild Deg. 14. 1925 INVENTOR Z'Zechz'cZ Wez'mraub BY ,,M

ATTORNEY Patented May 3, 1927.

UNITED STATES PATENT, OFF-ICE.

EZECHIEL WEINTRAUB, OF NEUILIiY-SUR-SEINE, FRANCE.

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Application filed December 14, 1928. Serial No. 680,691.

spot, it has heretofore been proposed to affix to the mercury cathode an emergent pointed stud or equivalent element made of either platinum or copper. These metals will function as intended to fix the cathode spot, 0 but have been found commercially impracticable on account of the facts that platinum is appreciably disintegrated by the ionic bombardment occurring in the operation of the device and copper dissolves in the mercury. In each instance the disintegrated metal forms a film-like coating on the walls of the receptacle to which the condensed mercury adheres. This coating is electrically conductive and, being formed on the in- I have found by experiment that certain.

metals having the properties of high refractiveness and high density are free from the above-mentioned objectionable characteristics of platinum and copper, in that they do not become disintegrated by the ionic bombardment and do not dissolve in the mercury. The metals which I have found to be most particularly adapted for this purpose are tungsten and molybdenum. Both of these metals are classified in the sixth group of Mendeleefs periodic table. Molybdenum has a specific gravity of 9.01 and tungsten of 19.6. .The melting oints of both these metals are above 2000 Another metal which may be utilized for the same purpose is tantalum. This latter metal is classified in the fifth group of Mensulating parts of the apparatus, is likely to.

deleefs periodic table, and has a specific gravity of 14.49 and a melting point above 2000 C.

From the foregoing it will be seen that the metalswhich have been found to be operative for the purpose set forth and free from the objectionable characteristics of platinum and copper may be defined as being included in the combined fifth and sixth groups of the periodic table and having specific gravities at least as great as that of molybdenum and a melting point greater than 2000 (3..

Not only may these metals be used individually for the purpose of this invention, but certain of their alloys may also-be successfully employed'due regard being had for the essential properties of high density and refractiveness, as well as for the practical necessity of selecting an alloy which may be satisfactorily worked.

' With reference to the accompanying drawing, Figs. 1, 2 and 3 show fragmentary crosssectional views of mercury vapor de-. vices illustrating three alternative embodiments of the invention.

In each figure A is a mercury cathode, B is a glass receptacle, and C is an auxiliary anode for starting the device in operation. D, E and F are the. electrode elements in accordance with this invention.

In Fig. 1, the electrode D is in the form of a rod, the upper end portion of which projects beyond the surface of the mercury cathode.

In Fig. 2, the electrode E is made of Wire or rod and its upper end portion formed.

In Fig. 3, the upper end ortion of the elegztrode F has the form 0, a cylindrical tu e.

The particular form of electode employed is inconsequentialethose illustrated being merely by way of example. For handling small currents, a rod electrode as in Fig.1 is generally employed, while for large curis spirally rents either a spiral or cylindrical electrode as in Figs. 2 and 3 is used.

In rectifiers not provided with artificial cooling means and intended to handle up to 40 amperes, it is advisable to allow from to 1 millimeter of'contact line per. ampere between the mercury and the electrode element at the surface of the mercury.

In mercury vapor devices in which the 'cathode 'spot is not fixed, it has been found that the minimum operating current is ap proximately 3 amperes. When the cathode spot is rendered stationary in accordance- With the present invention, the minimum operating current which may be realized is reduced to approximately 1 ampere. This is obviously a very distinct advantage.

I claim:

1. In a mercury vapor device including a mercury cathode, means for fixing the cathode spot comprising an electrode element in contact with said mercury cathode,

said electrode comprising metal classified within the combined fifth and sixth groups of the Mendeleef periodic system and having a specific gravity at least as great as that of molybdenum and not greater than that of tungsten and melting point above 2000 C. a

2. In a mercury vapor device including a mercury cathode, means for fixing the cathode spot comprising an electrode element in contact with said mercury cathode, said electrode comprising metal classified in the sixth group of the Mendeleef periodic system and having a specific gravity at least as great as that of molybdenum and melting point above 2000 C. l In a mercury vapor device including a mercury cathode, means for fixing the cathode spot comprising an electrode element in contact with said mercury cathode,

said electrode comprising metals classified within the combined fifth and sixth groups of the Mendeleef periodic system and having specific gravities at least as great as that of molybdenum and melting points above 2000 C.

4. A mercury vapor device including a. mercury cathode, means for, fixing the cathode spot comprising an electrode element in contact with said mercury cathode, said electrode comprising metals classified in the sixth group of the Mendeleef periodic system and having specific gravities at least as great as that of molybdenum and melting points above 2000 C.

5. In a mercury vapor device including a mercury cathode, means for fixing the cathode spot comprising a tungsten electrode element, said element being in contact with said mercury cathode.

6. In a mercury vapor device including a mercury cathode, means for fixing the cathode spot comprising an electrode element in contact with said mercury cathode, said electrode comprising tungsten and molybdenum and having a specific gravity at least as great as that of molybdenum and melting point above 2000 C.

7. In a mercury vapor device including a mercury cathode, means for fixing the cathode spot comprising an electrode element in contact with 'said mercury cathode, said electrode being made of an alloy comprising tungsten and molybdenum and having a specific gravity at least as great as that of molybdenum and melting point above 2000 C.

8. In a mercury vapor device including a mercury cathode, means for fixing the cathode spot comprising an electrode element in contact with said mercury cathode, said electrode being made of an alloy comprising tungsten, molybdenum and tantalum and having a specific ravity at least as great as that of molyb enum and melting 

